There's an old Firesign Theater sketch called "Temporarily Humboldt County." Some Native Americans are sitting around enjoying nature when the Spanish conquistadors show up with a priest. The conquistadors claim the land for Spain and Father Corona adds, "Oh! By the way, Domini Domini Domini, you're all Catholics now."

I was reminded of this sketch on Tuesday when Flickr decided I was a Christian.

Since Tuesday, if you visit any Flickr member's photos with a modern browser, you'll see three little snowflakes beside the Flickr logo. Click them and you'll be treated to a cascade of snowflakes over the page and all its photos, as well as a row of blinking Christmas lights at the top of the page. For an added treat, you can roll over the lights with your mouse and they'll pop, complete with sound effects. Click the little "[x]" beside the logo and it all goes away ... at least until the next page load when the three little snowflakes show up again.

Flickr is the community website that's closest to my heart. The site's founders are friends of mine and my wife worked there for 5 years. But more important than that, it's a community that I love. I've spent years uploading gigabytes of photos there, and my photostream has become a virtual home for me.

So it's distressing when someone puts Christmas lights on my virtual home. I'm not a Christian. I don't care how secular the holiday is nowadays. I know about the holiday's Pagan roots. None of that matters. The fact is, Christmas lights on a home are a signifier that the occupant is a Christian, the same way a mezuzah is a signifier of a Jewish occupant. These symbols have power, which is why we use them.

It's not just that Flickr is smearing Christmas "cheer" all over itself. As a non-Christian in a Christian country, I'm grudgingly used to that. (Though it would be nice if clicking that "[x]" set a cookie that prevented it from loading on the next pageview.) It's that my Flickr stream is my personal identity in the Flickr community. That's my face there at the top. Flickr has added a Christian signifier to my virtual home and I have no way to remove it. In the eyes of the rest of the community, Flickr has turned me into a Christian.

I'm aware that Flickr has done other Christmassy things in the past. For a while, you could add a string to a URL to make it snow. Other years, if you put a note on a photo with a special phrase ("ho ho ho hat"), a Santa hat would appear. But these were all secret easter eggs. (Easter! We can't even talk about this without more Christian holidays coming up.) And in the case of the notes, I could easily remove them and control who has the power to leave notes on my photos. But this year's festivities are unavoidable. Don't like the Christmas lights on your virtual home? Too bad.

When you begin a virtual community, you're building for yourself. You can safely assume that most of the community is like you. But as it grows, the community becomes more diverse. If you're extremely lucky, some of your members will invest themselves so much, they'll come to view the site as a kind of home. (This, by the way, is the success case. It's what you design for.)

Flickr is now a truly global community. I'm sure that a huge percentage of their members don't celebrate Christmas. Heck, half the world is in summer right now, so I'm not sure what they make of the snowflakes. Flickr should know this better than anyone.

The decision to put Christmas lights on all of their members' virtual homes shows a profound lack of understanding for who their users are and what those symbols mean. It's the kind of decision you make when you're so enamored of a technology you forget to think through the social implications of what it'll do to the real people who love your site - real people who are not exactly like you. Making your members feel unwelcome in their own homes is the first step in the decline of a community.

The lights and snowflakes will go away after Christmas, but I'll still be incredibly disappointed in one of my all-time favorite sites.

Derek Powazek has been designing and building community systems online since 1995. He is the author of Design for Community: The Art of Connecting Real People in Virtual Places, the cofounder of JPG Magazine, editor of Fray, and the founder/CEO of Fertile Medium, an online community consultancy. He only criticizes because he cares.